Chengshi guidao jiaotong yanjiu (Jan 2024)
Innovative Practices in Enhancing the Inherent Safety of Shield Tunnel Structures in Shanghai Rail Transit
Abstract
[Objective] Shield tunnels are inherently flexible structures characterized by multiple joints. Due to factors such as initial structural defects, varying surrounding loads, environmental deterioration and inadequate maintenance, shield tunnels are susceptible to deformation exceeding allowable limits, excessive leakage and durability degradation. Solely relying on reinforcement and rectification during operational phase cannot comprehensively address these issues. Moreover, with the expansion of rail network, maintenance costs and the expense of night operation window time resources are also increasing drastically, ultimately affecting the operation-maintenance efficiency and quality of the entire urban rail transit network. Therefore, it is necessary to research technical measures for enhancing the inherent safety of shield tunnel structures (hereinafter abbreviated as ′shield inherent safety′). [Method] The primary defects in Shanghai rail transit shield tunnels and the main factors affecting the shield tunnel structure safety are analyzed. The technical measures for enhancement and the innovative practices for guarantee of shield inherent safety adopted by Shanghai rail transit are introduced. [Result & Conclusion] The technical measures implemented by Shanghai rail transit to enhance shield inherent safety include optimizing and expanding the internal diameter of shield tunnels, adopting a staggered joint assembly method, and improving joint sealing and waterproof design. The innovative practices ensuring the shield inherent safety involve the use of a novel shield tunnel structure with pre-embedded socketed segments, the utilization of push-and-assemble synchronized intelligent shield tunneling equipment, and tunnel smart construction technology. By addressing the shield inherent safety at the source and optimizing tunnel structure design, innovating assembly techniques, and employing intelligent equipment, Shanghai rail transit aims to improve the forming quality of shield tunnels during the construction phase and reduce initial structural defects. This approach can lower the likelihood of structural damages during the operational phase, laying a solid foundation for the long-term safe operation of tunnels.
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